A turbocharger is an apparatus which rotates a turbine using pressure and thermal energy of exhaust gas generated during the power strokes of an engine, and thus, rotates an impeller provided on the same rotating shaft as that of the turbine so that air drawn through an air cleaner is pushed into a combustion chamber of the engine. Here, intake air is supercharged and an air charge rate is therefore increased, thus promoting improvement in output of the engine and reduction in exhaust gas emissions.
A supercharger is also provided in some vehicles, which is operated using power of an engine or a motor to supercharge intake air for the engine, thus enhancing the output of the engine.
However, even when both the supercharger and the turbocharger are installed together, because exhaust gas is discharged without being increased in temperature to sufficient degree at start of a vehicle, that is, during cold M start, fresh air that is not heated is supplied to an intake manifold. Thus, there is a problem of deterioration in characteristics of exhaust gas such as CO, tetrahydrocannabinol (THC), etc. due to combustion instability by temperature reduction in a late period of a compression stroke of a cylinder when the engine is operated in the cold start.
The foregoing is intended merely to aid in the understanding of the background of the present disclosure, and is not intended to mean that the present disclosure falls within the purview of the related art that is already known to those skilled in the art.